Astronomers find most Earth-like planets yet

New York, April 19 – Astronomers working with NASA's Kepler planet-finding spacecraft said on Thursday that they had found the most Earth-like worlds yet known in the outer cosmos, a pair of planets that appear capable of supporting life and that orbit a star 1,200 light-years from here in the constellation Lyra.

 

The newly discovered planets are the two outermost of five worlds circling a yellowish star slightly smaller and dimmer than our Sun, heretofore anonymous and now destined to be known forever in the cosmic history books as Kepler 62. These planets are roughly half again as large as the Earth and are presumably balls of rock, perhaps covered by oceans with humid cloudy skies, although that is at best a highly educated guess.

 

Looming brightly in each other's skies, the two planets circle their star at distances of 37 million and 65 million miles, about as far apart as Mercury and Venus in our own solar system. Most significantly, their orbits place them both in the "Goldilocks" zone of lukewarm temperatures suitable for liquid water, the crucial ingredient for Life as We Know It.

 

"This is the first planet that ticks both boxes," Dr Charbonneau said, speaking of the outermost planet, known as Kepler 62f. "It's the right size and the right temperature." Kepler 62f is 40 percent bigger than Earth and smack in the middle of the habitable zone, with a 267-day year. In an interview, Mr Borucki called it the best planet Kepler has found

 

Its mate, known as Kepler 62e, is slightly larger — 60 percent bigger than Earth — and has a 122-day orbit, placing it on the inner edge of the Goldilocks zone. It is warmer but also probably habitable, astronomers said.

 

The Kepler 62 system resembles our own solar system, which also has two habitable planets: Earth and Mars, which once had water and would still be habitable today if it were more massive and had been able to hang onto its primordial atmosphere.

 

Kepler 62's newfound worlds are not still not quite small enough to be considered strict replicas of Earth, but the new results have strengthened the already rabid conviction among astronomers that the galaxy is littered with billions of Earth-size planets, perhaps as many as one per star, and that astronomers will soon find Earth 2.0, as they call it — our lost twin bathing in the rays of an alien sun.

 

In the case of Kepler 62, said Natalie Batalha of San Jose State University, a Kepler mission scientist, the astronomers had determined the composition of the new planets by comparison to three earlier objects that had similar sizes and turned out to be rocky.